Field of the Invention
This invention relates to a surveillance device employed to detect the occurrence of an anomalous phenomena within a surveilled area and to record a picture image of the anomalous phenomena.
In facilities where non specified individuals enter and leave public areas (for example, banks, businesses, etc.), or where danger could arise due to the presence of a foreign object (for example, electric power plants, power transmission equipment), it has been the conventional practice to install video cameras at specific locations, and survey the area for the presence or absence of an anomalous occurrence by means of checking the picture images taken by the video cameras. In this type of surveillance, a method of real time surveillance involving a human monitor may be employed, or alternatively, the image of the surveilled area may be recorded on video tape and, by playing the video tape back after an anomalous event has occurred, the anomaly may be examined and resolved. It is noted here that the term "anomalous phenomena" as stated throughout this specification refers to an image which moves across the screen at a specific speed or undergoes changes (contrast) with respect to the still background image.
However, it is not generally possible to know when an anomalous phenomena will occur. Therefore, in conventional surveillance devices for detecting anomalous phenomena, when carrying out surveillance in real time, a person must be constantly employed at a monitor without regard, for example, to whether or not an anomalous event actually takes place. Thus, such monitoring to detect an anomalous phenomena, the occurrence of which cannot be predicted, cannot be regarded as very efficient.
Further, even in the case where not monitoring in real time, irrespective of the actual presence or absence of an anomalous phenomena, it is still necessary to constantly record the image of the surveilled area on video tape in order to capture an anomalous occurrence, the timing of which cannot be predicted. In this case, it is necessary to employ a method of using video tape capable long play recording or a method wherein intermittent recording is carried out.
Thus, as described above, with the conventional anomaly surveillance devices, the problem occurs in that it is not possible to carry out an efficient surveillance. Further, because it is not possible to specify when an anomalous event will occur, an additional drawback is present in the conventional devices in that, in the worst case scenario, the anomalous occurrence may be missed.